I have the same problem with 3 glow plugs on my '97 F250 Powerstroke (206,000 miles). My mechanic is ready to remove both cylinder heads tomorrow due to siezed glow plug electrodes. He has tried (for several days) penetrating oil with no results. I am concerned at this point about debris from the electrode being left inside. Is it best to remove the heads now or should we keep on trying the penetrating oil method? If the heads are removed, what gotcha's are there that we should look for? How mush should head removal cost on a powerstroke?

Any advice would be appreciated.
Thanks,
rus7755